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Make const slide less silly (#2557)

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A constant named ZERO that does not contain zero seems pretty silly!

This also shows an example of a const fn.
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Dustin J. Mitchell 2025-01-16 04:18:29 -05:00 committed by GitHub
parent cb5409052a
commit 3291cb6c62
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1 changed files with 10 additions and 2 deletions
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src/user-defined-types/const.md
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@ -11,10 +11,18 @@ they are used:
```rust,editable
const DIGEST_SIZE: usize = 3;
const ZERO: Option<u8> = Some(42);
const FILL_VALUE: u8 = calculate_fill_value();
const fn calculate_fill_value() -> u8 {
if DIGEST_SIZE < 10 {
42
} else {
13
}
}
fn compute_digest(text: &str) -> [u8; DIGEST_SIZE] {
let mut digest = [ZERO.unwrap_or(0); DIGEST_SIZE];
let mut digest = [FILL_VALUE; DIGEST_SIZE];
for (idx, &b) in text.as_bytes().iter().enumerate() {
digest[idx % DIGEST_SIZE] = digest[idx % DIGEST_SIZE].wrapping_add(b);
}